Notredame, C.-E. | bioRxiv Science

bioRxiv2020

Life trajectories towards suicide: developmental role and specificities of adolescence

ObjectiveConsidering that adolescence is a crucial period of allostatic maturation, we aimed at testing whether it represents a breakpoint in adversity trajectories to suicide and, relatedly, whether life trajectories of adolescents who died by suicide differ from those of adult counterparts. MethodIn 303 individuals who died by suicide, a panel of experts derived longitudinal burden of adversity ratings from extensive clinical interviews conducted with informants. Piecewise Joint Latent Class Models allowed to identify patterns of adversity trajectories and test the introduction of breakpoints in life-paths. The classes inferred from the optimal model were compared in terms of socio-demographics, psychopathology and nature of experienced events. ResultsThe most accurate model derived 2 trajectory patterns with a breakpoint in early adolescence. In the first class (n = 43 individuals), the burden of adversity increased steadily from birth to death, which occurred on average at 23 (SE = 1.29). In the second class (n = 259), where individuals died on average at 43 years (SE = 0.96), the burden of adversity followed a similar trajectory during infancy but stabilized between ages 10 and 14 years and rebounded at about 25. The classes differed in terms of childhood family stability, occurrence of dependent events, distal exposure to suicide and intra-family sexual victimization. ConclusionAlthough subject to inherent limitations of the retrospective designs, our results encourage clinicians and researchers to pay greater attention to the diathetic maturation processes occurring during adolescence when considering suicidal behaviors in young people.

developmental biology↗

bioRxiv2019

Circular inference in bistable perception

When facing fully ambiguous images, the brain cannot commit to a single percept and instead switches between mutually exclusive interpretations every few seconds, a phenomenon known as bistable perception. Despite years of research, there is still no consensus on whether bistability, and perception in general, is driven primarily by bottom-up or top-down mechanisms. Here, we adopted a Bayesian approach in an effort to reconcile these two theories. Fifty-five healthy participants were exposed to an adaptation of the Necker cube paradigm, in which we manipulated sensory evidence (by shadowing the cube) and prior knowledge (e.g., by varying instructions about what participants should expect to see). We found that manipulations of both sensory evidence and priors significantly affected the way participants perceived the Necker cube. However, we observed an interaction between the effect of the cue and the effect of the instructions, a finding incompatible with Bayes-optimal integration. In contrast, the data were well predicted by a circular inference model. In this model, ambiguous sensory evidence is systematically biased in the direction of current expectations, ultimately resulting in a bistable percept.

neuroscience↗